Pneumatic switch



- Jan 27, 1931. w. J. WILLIAMS 1,790,564

PNEUMATIC SWITCH Filed April 2. 192a 2 Sheets-Sheet '1 v i425 16 .24 Y r k 1Q 23 1 I 20 :l m 26 1 5 3 Jan. 2'7 1931; w. .1. WILLIAMS PNEUMATIC SWITCH Filed Apri1'2, 1928 2 Sheets-Sheet 2 Patented Jan. 27, 1931 UNITED STATES PATENT OFFICE WILLIAM J'. WILLIAMS, OF CHICAGO, ILLINOIS, ASSIGNOR, BY MESNE ASSIGNMENTS, TO

JOHN C. KERNCHEN, OF CHICAGO, ILLINOIS rnnnmarrc swrron This invention relates to improvements in pneumatic switches and is particularly adapted for use in connection with automatic starting means for motor vehicles, such as is covered by my co-pending application, filed May 13, 1927, Serial No. 191,121, of which the present application is, in part, a division.

The principal object of the invention is to provide an improved switch adapted to be controlled by fluid pressure such as for instance sub-atmospheric pressure, developed by the suction or intake strokes of the'engine.

A further object is to provide a switch having a quick acting diaphragm for opening and closing the circuit through contacts carried by the switch.

Other objects relate to the provision of a durable positive acting switch which has no parts likely to be damaged by heat which can be adjusted to operate at ditferent pressure differentials, and which can be manufactured as a compact, readilymountable unit.

Further objects relate to various features of construction and arrangement of parts 7 which will be apparent from a consideration I of the following specifications and accompanying drawings, wherein: n

Fig. 1 is a vertical sectional. elevation through one form of switch;

Fig. 2 is a view of the same with the cover removed. I

Fig. 3 is a diametrical section of a modified form of switch taken on line 3-3 of Fig. 4;

Fig. 4 is a sectional view of the cover'taken V on line 1- 4 of Fig. 5;

Fig. 5 is a sectional view taken on line 55 of Fig.4,

Fig. 6 is a perspective view of the interior of the cover; Fig. 7 is a side elevation of the switch shown in Fig. 8; and

Fig. 8 shows an assembled switch unit. In Figs. 1 and'2, the switch is shown as comprising a base 10 of insulating material secured by nuts 11 on the tube 12, the switch bein adapted to be secured on a vacuum line 13 '0" an automobile engine by means of suitable clamping members 14, which are described more in detail in my above mentioned 5 application.

' Secured to the inner end of the tube 12, is a plate 15, to the periphery of which is secured a diaphragm 16. As shown, the diaphragm has its edge 17 folded or crimped around the periphery of the plate 15, to form an airtight construction. Inwardly of the edge or flange 17, the diaphragm is depressed or corrugated as at 18, this depression en: circling an outwardly convexed central portion19. The diaphragm 16 is preferably formed of metal, and the convexity of the same is such that by the removal of pressure from the interior thereof, it will move inwardly with a snap-action. This quick acting diaphragm is made use of in controlling a circuit through the switch.

The conducting strap 20 is secured at one end by means of a bolt 21 to the base 10, and at its, other end to said base by the terminal screw 22. Secured to the conducting strip 20, butinsulated therefrom, is' a spring 23. This spring is secured in position by means of a bolt 24, connecting which and the binding post 25, is a short conductor 26. The spring is free at one end as shown, and when in the full line position shown in Fig. 1, it makes contact with an adjusting screw 27, which passes through the strip 20. When the spring is in contact with the screw 27, current can flow through terminal 25, wire 26,

terminal 24 (which is insulated from the strip 20) spring 23, screw 27, strip 20 to the other terminal 22.

Assuming that a partial vacuum is created in the suction chamber between the plate 15 and diaphragm 16, the central portion 19 of the diaphragm will snap inwardly, thereby permitting the spring23 to'move to the dotted line position and out of contact with the screw 27, thus opening the circuit. Should the engine stop, thereby terminating the suction, the diaphragm 19, will snap back to the position shown in which the insulating I member 28 forces the spring 23 back into contact with the screw 27, and thus closes the circuit through the switch.

In the form of'the invention shown in Fig. 3, a base 30 is formed preferably of insulating material, such as bakelite, the base having an inserted metal ferrule or threaded member '31, adapted to receive a threaded tube 32 which may be connected tothe source of power such as the vacuum line of a vehicle or the intake manifold of the engine. A circular rib33 is formed on the inner surface of the base 30, to which is secured a flexible diaphragm 34,,havinga' peripheral flange 35, which closely engages the outer surface of. the rib. To make an air-tight joint, cement may be used between the contacting surfaces of the flange and rib. The diaphragm is slightly depressedjust inwardly of the on the base, as by suitable screws. Secured wires 40, 40 on the switch cover 40 by to the cover 40, by means of a terminal post 43, is a leaf spring 44,- which is centrally bowed, as at 45, in a direction toward the diaphragm 34. 'Interposed between the cover and spring is a strip of insulating material such as fibre 46, which insulates the free end of the spring 44 from the inner end of the adjustable threaded terminal 47 An adjusting screw 48, passes through a central aperture 46 in the insulating strip 46, and in the full lineposition shown in Fig. 3, the screw contacts with the spring 44, whereby the circuit between the terminals 43 and 47 is closed .by the spring 44, screw 48 and the imbedded conducting strip 49. This strip 49 can of course be omitted as .its purpose is to permit of the greater spacing of the lead necting them to theterminals 43, 47 insteadof to terminal 43 and screw 48. The strip 49 is tapped to receive the threaded screws 47 and 48, and thus makes good electricalcontact with the same. moves in a direction-toward the base,'or collapses due tothe exhaustion of pressure in the chamber 38the spring 44moves'out'of contact with screwv 48 and this opens the circuit through the switch. By adjusting the screw 48 inwardly, it will beseen that the diaphragm .34,'cannot assume its fully extended position and that it will thereafter snap inwardly under less vacuum than Where the screw 48 is adjustedin the reverse direction. By means of the screw 48, therefore,: the switch can be caused to cut out or open the circuit at the desired pressure. As the spring 44 is under compres- \sion' in theposition shown in Fig. 3, it will follow the diaphragm when the latter snaps inwardly upon the exhaustion ofthe air from the chamber 38, By adjusting the screw 47,

the tensionof the spring 44 against the dia- COH- When, the" diaphragm 34 phragm can be increased, and while the' pressed position to hold it against the return movement. By adjusting the screw 47, there fore, it is possible to regulate the switch to cut in under predetermined pressure'values. The screws 47 and 48, therefore, provide means for varying the pressure differentials at which the switch will open and close the circuit.

Although I have shown and described certain features of my improvements for the purpose of illustration, it will be apparent that various changes may bemade therein without departing from the spirit of the inventi on as defined in' the appended claims.

What I claim is 1. A pneumatic switch comprising a base provided with a pressure responsive diaphragm for effecting the opening and closing ofa circuit, a cover for said casing provided with a conducting strip, a terminal in said cover, a leaf spring contacting with and secured at one end by said terminal and being adapted to bear against said diaphragm, a second terminal having electrical contact with said conducting strip, said second contact being insulated from said spring and being arranged to vary the pressure of the spring against the diaphragm for regulating the circuit closing action of the. switch and a screw passing through said strip and adapted to contact with said spring for closing the circuit adapted to be secured to said base, said cover being provided with a terminal, a spring secured .at one end by said terminal, said spring being disposed diametrically of said cover and having a bowed portion tending to,

'move normally in the direction of said dia-Ptaz phragm, an adjusting screw in the cover adapted to make contact with "said spring -when the diaphragm is in extended position and'to limit the outward movement of the diaphragm, a second terminal in the cover insulated from said spring but arranged to compress the same against the diaphragm for varying the circuit opening action thereof,

and a conducting strip connecting said screw and second terminal for closing the circuit between the latter and said first terminal when the spring has been-moved into contact with said-screw by said diaphragm.

3. A pneumatic switch com rising a base of insulating material provide with a circu- 5 in rib, a metallic diaphragm having a flange adapted tofit over said rib to form a suction chamber, a tubular member in the base for effecting communication. between the chamber and a source of power, a boss in said chamm her for limiting the movement of the diaphragm inwardlyof the chamber, a cover adapted to be secured to said base, said cover being provided with a terminal, a spring secured at one end b said terminal, sa d spring 15 being disposed diametrically of said cover and having a bowed portion tendingto move normally in the direction of said diaphra an adjusting ,screw in the cover adapte to make contact with said spring when the dia- 20 phragm is in extended position and to limit the outward movement of the dia hragm and a second adjustable member in the cover insulated from the spring for varyin the pressure of the spring against the diap ra for 15 controlling the circuit closing action-t ereof, said terminal and said adjusting screw being bridged by said spring to close the circuit through the switch when the diaphragm is in outer osition; in so 4 switch comprising a flexible diaphragm operable byvariations in fluid pressure for controlling an electric circuit, a member enclosing said dia hragm, a air of electric terminals carried by said en osing mem- 35 her, a bowed leaf spring secured at one end by one of said terminals with a convex portion ofthespring bearing against said dia phragm when the latter is in extended posi tion, the other terminal bein adjustable'and 0 having its inner end insula from and bearing against the free end of said spring for varying the pressure of the spring against sai dia hragm, and an adjustable screw in said enc osing member electrically connected as to said adjustable terminal and cont-acting with said spring at a point opposite therpoint of contact of said spring and diaphra when the latter is in extended position 551 limiting-the movement ofthe diaphragm in '0 one direction and closing the circuit between v WILLIAM J. WILLIAMS. 

